(12,75-6 11/12 +14/8-7 2/15):(10 2/3-3 11/12)
((1275/100)-(83/12)+(14/8)-(107/15)):((32/3)-(47/12))=( (7650-4150+1050-4280)/600));((128-47)/12))=(270/600)*(12/81)=1/15
(12,75-6 11/12 +14/8-7 2/15):(10 2/3-3 11/12)=1\15